EduNinja
Learning objective

A1.2.6—DNA as a double helix

DNA forms a double helix from two antiparallel polynucleotide strands held together by hydrogen bonds between complementary bases in the molecule.

Syllabus
First assessment 2025
Objective
A1.2.6
Level
SL

Concept essentials

  • DNA as a double helix should be described using precise molecular vocabulary.
  • Structure and information must be kept separate: backbones provide continuity while bases carry sequence meaning.
  • Exam answers should match the command term and avoid adding unsupported extra claims.

Exam analysis

Question evidence linked specifically to this learning objective.

Chance of appearing9%of analysed past papers
Latest appearanceNovember 2024
Most common paperPaper1
Typical marks1–5

Common command terms

  • Describe
  • Explain
  • Deduce
  • Draw
  • Sketch

Exam question appearances

November 2024Paper1 SL · TZ210[ 1 ]A1.2.6—DNA as a double helix
May 2024Paper1 SL · TZ19[ 1 ]A1.2.6—DNA as a double helix
November 2023Paper1 SL · TZ211[ 1 ]A1.2.6—DNA as a double helix
November 2023Paper1 SL · TZ111[ 1 ]A1.2.6—DNA as a double helix
November 2020Paper2 SL · TZ04(a)[ 3 ]A1.2.6—DNA as a double helix

Coverage 2012–2024 · Updated 14 Jul 2026

Focused stepA1.2.6—DNA as a double helix